Vivitar is a brand name. They make no lenses. It's probably a Cosina 28-210 with Vivitar name on it. Also sold under the Phoenix name same specs. List price is about $130 retail. So, its a very inexpensive lens.

Yeah, I only found manual focus when searchiing just now. The guy swears it says AF on the lens, but then again, it is Craigslist so there's really no telling. I really appreciate your help, I was getting nowhere on my own.